Detailed Sedimentology and Inorganic Geochemistry of the Dolgeville Formation and Utica Group of the Central Mohawk Valley, NY

Transcription

1 Detailed Sedimentology and Inorganic Geochemistry of the Dolgeville Formation and Utica Group of the Central Mohawk Valley, NY Daniel Miserendino Jeffrey T. Pietras

2 Introduction and Purpose Drill cores present continuous, unweathered rock record ideal for detailed sedimentologic and geochemical studies Utica Group (Indian Castle Shale and Flat Creek Shale) Trenton Group (Dolgeville Fm.) Study the evolution of Ordovician foreland basin by investigating: Source terrain Seawater chemistry Sea level changes Depositional processes Tectonic processes

3 Geologic Setting d.edu/departments/inv ertpaleo/trenton/ Early Ordovician: Passive margin off southwest Laurentia formed. Mid-Late Ordovician: Carbonate platform developed. Onset of Taconic Orogeny.

4 Study Area N Legend: Core Location Major city 150 km 75NY-5 N 75NY-7 74NY-5 Mohawk River 75NY-2 30 km

5 Stratigraphy modified from Brett and Baird, 2002

6 Stratigraphy -This Study -Spiegel, expected Jones, Saboda and Lash, 2014 modified from Brett and Baird, 2002

7 Depth (ft) Honey Hill Disconformity 0 75NY-7 74NY Upper Indian Castle Shale 200 Lower Indian Castle Shale Indian Castle Shale Collected near Honey Hill Rd, Newport, NY Thruway Disconformity 75NY-7 G. Baird 300 Dolgeville Fm Trenton Group Limestone Dolgeville Fm. E. Spiegel Wintergreen Park Interval mm 74NY km Flat Creek Shale

8 .5 ft Dolgeville Formation Interbedded limestone and black mudstone Interpretation: Alternating turbidites and low energy, pelagic mud deposition Near County Home, NY E. Spiegel Core 75NY-7 E. Spiegel

9 Utica Group Black mudstone Dino-Lite Edge Digital Microscope Interpretation: Low energy Pelagic Organic matter accumulation and pyrite

10 Banded black mudstone Interpretation: Thin turbidites Change in pelagic sediment

11 1 in Graded gray calcareous silty mudstone Fining upwards 75NY-7 74NY-5 Fining upwards Black mudstone 5 mm Interpretation: Turbidites Black mudstone

12 Cross-stratified calcareous silty mudstone 5 mm 5 mm Interpretation: Turbidites Contourites

13 Dark gray silty mudstone Interpretation: Increased silt and sand input More siliciclastic input, less carbonates

14 1 in Matrix supported sandy mudstone Stratigraphic up 75NY-7 Interpretation: Debrite

15 150 ft Facies Summary: 74NY-5 Upper Indian Castle Shale Lower Indian Castle Shale Dolgeville Fm. Trenton Group Limestone 75NY-7 Black mudstone Banded black mudstone Black mudstone Banded black mudstone Graded gray calcareous silty mudstone Dark gray silty mudstone Matrix supported sandy mudstone Cross-stratified calcareous silty mudstone Graded gray calcareous silty mudstone Black mudstone Black mudstone Banded black mudstone Graded gray calcareous silty mudstone Cross-stratified calcareous silty mudstone Matrix supported sandy mudstone Indian Castle Shale Dolgeville Fm. Wintergreen Park Interval Flat Creek Shale

16 150 ft Depositional Summary: 74NY-5 75NY-7 Upper Indian Castle Shale Pelagic Indian Castle Shale Lower Indian Castle Shale Dolgeville Fm. Trenton Group Limestone Pelagic Turbidites (calcareous, siliciclastic) Debrites Turbidites Pelagic Pelagic Turbidites (calcareous) Debrites Dolgeville Fm. Wintergreen Park Interval Flat Creek Shale

17 XRF and Rock Hardness Bruker Tracer III pxrf Settings Mg to Mn Fe to Mo kv µa Other Helium Yellow Filter Measured elements: Mg, Al, Si, P, S, K, Ca, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Pb, Se, Th, Rb, U, Sr, Y, Zr, Nb, Mo Proceq Equotip Piccolo samples 2800 samples Leeb s Hardness: Indentation hardness measures resistance to material deformation

18 Leeb's Hardness Leeb's Hardness Leeb s Hardness Crossplots Al (wt %) Ca (wt%) Similar trend for K, Th, and Si Soft= Clay Hard= Carbonate

19 Honey Hill Disconformity (96 ft)

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22 Summary and Future Work Sub-centimeter lithologic description of the entire Utica Group in NY has revealed a variety of unique facies Pelagic deposition, turbidity currents, debris flows and possible contour currents contributed to deposition of the Utica Group and Dolgeville Fm Chemostratigraphy at 3-inch intervals may help elucidate cryptic, chronostratigraphic horizons such as the lower and upper Indian Castle Shale contact Leeb s Hardness values have a negative correlation with Al, K, Th, and Si (clay mineral rich softer), and a positive correlation with Ca (carbonate beds harder) Future Work: Build stratigraphic columns to compare to XRF and hardness data Millimeter-scale XRF analysis with core scanning table Correlate litho- and chemostratigraphy to other cores Investigate patterns and cyclicity in XRF data (Fourier Analysis)

23 Thank You Special thanks to: Sigma Alpha Mu Foundation, for funding part of this research Brian Slater and the NYS Museum, for helping us move cores to Binghamton Gordon C. Baird, for general discussions and donating hand samples Proceq, for letting us borrow the Equotip Piccolo 2 for rock hardness testing